The long-term objective of this project is to develop an understanding of the development of aggressive behavior patterns among boys and girls sufficient to devise effective interventions with both aggressive children and those who are frequent victims of aggression. There are two immediate goals to the present proposal. One is to advance our understanding of aggression in childhood beyond the focus on individuals identified as highly aggressive to an understanding of the way aggressive relations evolve between pairs of individuals. Evidence from current work shows that 75% of aggressive behavior occurs among only 30% of the dyads existing among groups of preadolescent black males. Intensive analyses of video records of interactions of these dyads in newly formed peer groups will be directed at articulating the development of high mutually aggressive pairs and asymmetrically aggressive pairs, some of which can be characterized as bully- victim pairs. Attention to the distinction between reactive and proactive forms of aggression established in previous work will guide this inquiry, as will attention to the social consequences of behavior patterns. The second major objective of this proposal is to conduct with preadolescent black girls parallel lines of research to those already advanced with boys. In part, the rationale for this is the evidence that adolescent females have become increasingly involved in aggressive behavior, delinquency, and violent criminal acts over the past three decades and, in part, because peer rejection occurs as frequently among girls as boys in low income black populations and is highly related to aggression. Quasi- experimental peer group methodologies developed with boys will be utilized with preadolescent female samples, and videotape analyses of group behavior and aggressive episodes will be carried out in addition to the same dyadic analyses proposed for the male data.